Since the earliest development of clock mechanisms several hundred years ago, clock devices have increasingly become more sophisticated in their drive mechanisms and in the information displayed. Whereas early clocks simply indicated time, other clocks have been developed which indicate other useful information such as month, day, year, phase of the moon, elapsed time, and the like. Indeed, the variety of information which can be produced by various clock devices is great. Of particular interest, though, for the scope of the present invention, are clock devices which generate tidal information. Such clock devices, when set for a particular geographic location, will indicate the occurrence of low tides, high tides and the time prior to the occurrence of the low and high tide states.
The need for such a tide clock has been recognized in the past but the solution to such need has been accomplished differently than that shown in the present invention. For example, U.S. Pat. No. 3,921,383 issued Nov. 25, 1975 to Leone discloses a tide clock wherein a stationary dial is provided with index markings correlated to low and high tides. The clock drive mechanism drives a clock hand which is read against the dial to indicate low and high tide conditions as well as the time interval before the low and high tide conditions. U.S. Pat. No. 4,014,163 issued Mar. 29, 1977 to Wisser discloses a similar dial having tide indications. Again, a hand is driven by the clock mechanism to register the tide conditions. Another example of prior art is shown in U.S. Pat. No. 3,708,971 issued Jan. 9, 1973 to Wlodyka. Here, an outer dial is provided with indicators of high and low tides, and an indicator dial is indexed with temporal markings which are read against the concentric indicators of the outer dial. U.S. Pat. No. 4,412,749 issued Nov. 1, 1983 to Showalter shows a digital tide indicating clock.
Other examples of tide clocks are shown in the following patents:
______________________________________ Pat. No. Issue Date Inventor ______________________________________ 569,340 13 October 1896 A. A. Low 2,252,074 12 August 1941 W. H. Gulesian 2,677,928 11 May 1954 W. S. Haynes 3,248,866 3 May 1966 A. F. Spilhaus 3,524,313 18 August 1970 G. W. Wood 3,703,804 28 November 1972 G. T. Appelberg 3,823,544 16 July 1974 A. L. Terrence 3,825,181 23 July 1974 P. M. Banner 3,982,104 21 September 1976 P. M. Banner 4,035,617 12 July 1977 P. M. Banner ______________________________________
In all of the various tide clock devices, it is well recognized that, for a given location, high and low tides are periodic. Since the gravitational pull of the moon exerts the dominate influence upon bodies of water thus producing tide conditions in such bodies, the geometric location of such body of water, in space, when compared with the location of the Moon, determines tidal conditions. Therefore, the tide cycle is a function of both the rate of rotation of the Earth on its own axis as well as the rate of revolution of the Moon about the Earth. It has well been established that, generally speaking, the tide cycle operates on a period averaging 12 hours and 25 minutes. A further description of the basis of this may be found in U.S. Pat. No. 3,982,104, noted above. As a result of this periodicity, various clock drive mechanisms are available which include, as one of their components, a drive shaft that rotates according to the tidal cycle.
Despite the advances made by the various art tide clocks, there remains a need to provide improved tide clocks which more graphically display tide condition data in an easy to understand format and in an aesthetically pleasing manner.